Image forming systems which exhibit superhigh contrast photographic characteristics (for example with a gamma value of at least 10) are required for improving the reproduction of continuous tones by means of screen dot images and for improving the reproduction of line images in the graphic arts field.
The methods in which hydrazine derivatives are used as disclosed, for example, in U.S. Pat. Nos. 4,224,401, 4,168,977, 4,166,742, 4,311,781, 4,272,606, 4,221,857 4,269,929, are well known as methods by which high contrast photographic characteristics can be obtained using stable developers. Photographic characteristics of high sensitivity with superhigh contrast can be obtained using these methods and the addition of high concentrations of sulfite to the development bath can be tolerated and so the stability of the developer in respect of aerial oxidation is greatly improved in comparison with that of a lith developer.
Typically, the sticking which occurs when contact is made between pieces of photographic material or when a photographic material is brought into contact with the apparatus which is used for processing has been alleviated in the past by the introduction of fine particle powders (matting agents) into the protective layers of the silver halide photographic materials to roughen the surface, and such an addition is often made with a view to improving the anti-static properties of the materials and for improving the vacuum contact properties when making contact exposures.
The matting agents normally used often have an average particle diameter of about 1 to 3 .mu.m. However, a fairly long time is required to achieve perfect contact when making contact exposures with vacuum contact when matting agents of such a size are used. Increasing the particle size of the matting agent and increasing the surface roughness of the photographic material is effective for resolving this problem, but when coating is carried out using simultaneous multi-layer coating apparatus the large size matting agent particles precipitate into the silver halide emulsion layer and this is disadvantageous in that there is a marked increase in the number of pinholes observed after exposure and development processing.
The use of matting agents which have cavities of average diameter at least 200 .ANG. as disclosed in JP-A-64-31149 is one way of improving these materials in respect of pinholes. (The term "JP-A" as used herein signifies an "unexamined published Japanese patent application.") Thus, in this case light scattering is caused by the presence of the cavities and pinholes are avoided. Furthermore, the use of matting agents which have a cavity inside each particle with a wall between the inside and the outside and in which the wall is porous so that the particles do not precipitate in the coating liquid has been disclosed in JP-A-62-163047. However, it is not possible to prevent the occurrence of pinholes using these methods in those cases where a matting agent of large size is used, and further improvement is very desirable.